U.S. patent application number 11/524140 was filed with the patent office on 2007-04-05 for coolant composition for fuel cell.
Invention is credited to Hiroshi Egawa, Nobuyuki Kaga.
Application Number | 20070075289 11/524140 |
Document ID | / |
Family ID | 34994002 |
Filed Date | 2007-04-05 |
United States Patent
Application |
20070075289 |
Kind Code |
A1 |
Egawa; Hiroshi ; et
al. |
April 5, 2007 |
Coolant composition for fuel cell
Abstract
Coolant compositions for fuel cells having at least one sugar
alcohol in a base component that resist oxidation of the base
component and the rise of the electric conductivity of the coolant
when the fuel cell is in use. Fuel cells including coolant
compositions having at least one sugar alcohol in a base component.
Methods of making fuel cells including coolant compositions having
at least one sugar alcohol in a base component.
Inventors: |
Egawa; Hiroshi; (Gifu,
JP) ; Kaga; Nobuyuki; (Gifu, JP) |
Correspondence
Address: |
PATTERSON, THUENTE, SKAAR & CHRISTENSEN, P.A.
4800 IDS CENTER
80 SOUTH 8TH STREET
MINNEAPOLIS
MN
55402-2100
US
|
Family ID: |
34994002 |
Appl. No.: |
11/524140 |
Filed: |
September 20, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP04/04101 |
Mar 24, 2004 |
|
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11524140 |
Sep 20, 2006 |
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Current U.S.
Class: |
252/73 ; 429/438;
429/535 |
Current CPC
Class: |
H01M 2250/20 20130101;
H01M 8/04029 20130101; Y02E 60/50 20130101; C09K 5/10 20130101;
Y02T 90/40 20130101 |
Class at
Publication: |
252/073 ;
429/013 |
International
Class: |
C09K 5/00 20060101
C09K005/00; H01M 8/00 20060101 H01M008/00 |
Claims
1. A coolant composition for cooling a fuel cell unit, comprising a
base component and at least one sugar alcohol for oxidation
inhibition which is selected from the group consisting of
erythritol, xylitol, sorbitol, mannitol, inositol, quercitol,
palatinit, lactitol, maltitol, sucrose, raffinose, gentianose,
melezitose, planteose and stachyose, wherein the coolant
composition maintains the electric conductivity of the coolant at
10 .mu.S/cm or below.
2. The coolant composition of claim 1, wherein said base component
comprises at least one component selected from the group consisting
of water, alcohols, glycols and glycol ethers.
3. The coolant composition of claim 2, wherein said base component
comprises at least one component selected from the group consisting
of methanol, ethanol, propanol, butanol, pentanol, hexanol,
heptanol and octanol.
4. The coolant composition of claim 2, wherein said glycols are
ethylene glycol, diethylene glycol, triethylene glycol, propylene
glycol, 1,3-propanediol, 1,3-butanediol, 1,5-pentanediol and
hexylene glycol.
5. The coolant composition of claim 2, wherein said glycol ethers
are ethylene glycol monomethyl ether, diethylene glycol monomethyl
ether, triethylene glycol monomethyl ether, tetraethylene glycol
monomethyl ether, ethylene glycol monoethyl ether, diethylene
glycol monoethyl ether, triethylene glycol monoethyl ether,
tetraethylene glycol monoethyl ether, ethylene glycol monobutyl
ether, diethylene glycol monobutyl ether, triethylene glycol
monobutyl ether, and tetraethylene glycol monobutyl ether.
6. The coolant composition of claim 1, wherein said at least one
sugar alcohol is contained at 0.1 wt % to 20.0 wt %.
7. A fuel cell comprising a coolant composition, the coolant
composition comprising a base component and at least one sugar
alcohol for oxidation inhibition which is selected from the group
consisting of erythritol, xylitol, sorbitol, mannitol, inositol,
quercitol, palatinit, lactitol, maltitol, sucrose, raffinose,
gentianose, melezitose, planteose and stachyose.
8. The fuel cell of claim 7, wherein said base component comprises
at least one component selected from the group consisting of water,
alcohols, glycols and glycol ethers.
9. The fuel cell of claim 8, wherein said base component comprises
at least one component selected from the group consisting of
methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol
and octanol.
10. The fuel cell of claim 8, wherein said glycols are ethylene
glycol, diethylene glycol, triethylene glycol, propylene glycol,
1,3-propanediol, 1,3-butanediol, 1,5-pentanediol and hexylene
glycol.
11. The fuel cell of claim 8, wherein said glycol ethers are
ethylene glycol monomethyl ether, diethylene glycol monomethyl
ether, triethylene glycol monomethyl ether, tetraethylene glycol
monomethyl ether, ethylene glycol monoethyl ether, diethylene
glycol monoethyl ether, triethylene glycol monoethyl ether,
tetraethylene glycol monoethyl ether, ethylene glycol monobutyl
ether, diethylene glycol monobutyl ether, triethylene glycol
monobutyl ether, and tetraethylene glycol monobutyl ether.
12. The fuel cell of claim 7, wherein said at least one sugar
alcohol is contained at 0.1 wt. % to 20.0 wt. %.
13. A method of making a fuel cell, comprising the step of
contacting at least a portion of the fuel cell with a coolant
composition, the coolant composition comprising a base component
and at least one sugar alcohol for oxidation inhibition which is
selected from the group consisting of erythritol, xylitol,
sorbitol, mannitol, inositol, quercitol, palatinit, lactitol,
maltitol, sucrose, raffinose, gentianose, melezitose, planteose and
stachyose.
14. The method of claim 13, wherein said base component comprises
at least one component selected from the group consisting of water,
alcohols, glycols and glycol ethers.
15. The method of claim 14, wherein said base component comprises
at least one component selected from the group consisting of
methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol
and octanol.
16. The method of claim 14, wherein said glycols are ethylene
glycol, diethylene glycol, triethylene glycol, propylene glycol,
1,3-propanediol, 1,3-butanediol, 1,5-pentanediol and hexylene
glycol.
17. The method of claim 14, wherein said glycol ethers are ethylene
glycol monomethyl ether, diethylene glycol monomethyl ether,
triethylene glycol monomethyl ether, tetraethylene glycol
monomethyl ether, ethylene glycol monoethyl ether, diethylene
glycol monoethyl ether, triethylene glycol monoethyl ether,
tetraethylene glycol monoethyl ether, ethylene glycol monobutyl
ether, diethylene glycol monobutyl ether, triethylene glycol
monobutyl ether, and tetraethylene glycol monobutyl ether.
18. The method of claim 14, wherein said at least one sugar alcohol
is contained at 0.1 wt. % to 20.0 wt. %.
Description
CROSS REFERENCE TO RELATED PATENT APPLICATION
[0001] This application is a continuation-in-part of copending
international patent application PCT/JP2004/004101 entitled
"Coolant Composition For Fuel Cell" filed Mar. 24, 2004, the
disclosure of which is hereby incorporated herein by reference.
This application is related to U.S. patent application Ser. No.
11/121,358 filed May 4, 2005, U.S. patent application Ser. No.
11/330,015 filed Jan. 11, 2006, U.S. patent application Ser. No.
11/395,106, filed Mar. 31, 2006, and U.S. patent application Ser.
No. 11/441,550, filed May 26, 2006 entitled "COOLANT COMPOSITION",
the disclosures of which are each hereby incorporated herein by
reference.
TECHNICAL FIELD
[0002] This invention generally relates to a coolant composition
for cooling fuel cells, particularly for cooling automotive fuel
cells, which is capable of effectively inhibiting oxidation of the
base component of the coolant composition and maintaining the
electric conductivity of the coolant effectively low enough for a
long period of time.
BACKGROUND ART
[0003] A fuel cell unit generally comprises a plurality of
individual fuel cells arranged in stacks, which generates heat as
it generates electric power. In order to cool the stacked fuel
cells, a cooling plate is provided among every few fuel cells. Such
a cooling plate is provided with a winding coolant path or paths
where coolant circulates and cools the adjacent fuel cells.
[0004] If the electric conductivity of the coolant, which
circulates through the cooling plates within the fuel cell unit, is
"high", the electricity generated in the fuel cell unit leaks into
the coolant in the coolant paths, detrimentally lowering the
efficiency of the fuel cell unit. Accordingly, pure water, which is
"low" in electric conductivity and thus highly insulative, has been
generally used as coolant for fuel cell units.
[0005] However, in the case of a fuel cell unit which is used
intermittently, such as an automotive fuel cell unit, or a fuel
cell unit for a cogeneration system for home use, the temperature
of coolant circulating in the fuel cell unit falls to or close to
the atmospheric temperature when the fuel cell unit is not in use.
When the fuel cell unit where pure water is used as coolant is kept
at rest for long below the water freezing point, the pure water
coolant gets frozen and likely damages the fuel cell unit
physically by expansion and deteriorates the performance of the
fuel cell unit.
[0006] In order to prevent such damages and deterioration, use of a
glycol or alcohol as a base component may be considered.
[0007] However, a glycol or alcohol, when used as a base component
of coolant for a fuel cell unit, will produce ionic substances in
the coolant from oxidation of such a base component, which may be
negligible at first, though. The produced ionic substances will
eventually accumulate and gradually but steadily raise the electric
conductivity of the coolant.
[0008] In order to prevent such accumulation of ionic substances,
removing the ionic substances by arranging ion exchange resin
filters in the coolant paths of a fuel cell system may be
considered.
[0009] However, ion exchange resin filters are fast degraded
through use because the resin is consumed through removal of the
ionic substances produced by the oxidation of the base component,
quickly losing their effectiveness.
[0010] Accordingly, it is an object of the present invention to
provide a coolant composition for fuel cells, which is capable of
effectively inhibiting oxidation of the base component of the
coolant composition and maintaining the electric conductivity of
the coolant effectively low for an extended period of time.
SUMMARY OF THE INVENTION
[0011] The coolant composition of the present invention is
characterized by containing at least one specific sugar alcohol in
the base component. The base component of the coolant composition
of the present invention has a low electric conductivity and
sufficient anti-freezing property. Preferably, the base component
of the coolant composition of the present invention comprises at
least one component selected from water, alcohols, glycols and
glycol ethers.
[0012] Such alcohols may be selected from methanol, ethanol,
propanol, butanol, pentanol, hexanol, heptanol and octanol.
[0013] Such glycols may be selected from ethylene glycol,
diethylene glycol, triethylene glycol, propylene glycol,
1,3-propanediol, 1,3-butanediol, 1,5-pentanediol and hexylene
glycol.
[0014] Such glycol ethers may be selected from ethylene glycol
monomethyl ether, diethylene glycol monomethyl ether, triethylene
glycol monomethyl ether, tetraethylene glycol monomethyl ether,
ethylene glycol monoethyl ether, diethylene glycol monoethyl ether,
triethylene glycol monoethyl ether, tetraethylene glycol monoethyl
ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl
ether, triethylene glycol monobutyl ether, and tetraethylene glycol
monobutyl ether.
[0015] The coolant composition of the present further contains at
least one specific sugar alcohol in its base component to
effectively inhibit oxidation of the base component and prevent the
electric conductivity from rising beyond an acceptable level or 10
.mu.S/cm in order to maintain the electric power generating
capacity of the fuel cell unit above a satisfactory level. The
coolant composition of the present invention maintains the electric
conductivity within the range 0 .mu.S/cm-10 .mu.S/cm even after a
long use.
[0016] Such sugar alcohols may be selected from erythritol,
xylitol, sorbitol, mannitol, inositol, quercitol, palatinit,
lactitol, maltitol, sucrose, raffinose, gentianose, melezitose,
planteose and stachyose. Among them, sorbitol mannitol and lactitol
are especially preferred as they are excellent in oxidation
inhabitation as well as easy to handle and obtain.
[0017] Preferably, at least one sugar alcohol is contained in the
base component of the coolant composition of the present invention
in the range from 0.1 wt % to 20.0 wt % of the base component.
Efficient oxidation inhibition will not be provided if the content
is below this range and waste will result if the content is above
this range.
[0018] The coolant composition of the present invention may
additionally and selectively contain in its base component an
amount of a caustic alkali for pH adjusting, dye, antifoaming agent
and/or antiseptic, and/or an antirust agent such as a phosphate,
nitrate, nitrite, molybdate, tungstate, borate, silicate, sulfate,
sulfite, carbonate, amine salt, and triazole within a range that
will not adversely affect the electric conductivity of the coolant
composition.
EMBODIMENTS
[0019] The present invention is described in more detail below
based on preferred embodiments as compared with comparisons. Table
1 shows the components of preferred embodiments 1-3 of the present
invention and comparisons 1-5, where embodiment 1 consisted of a
base component of ethylene glycol (antifreeze agent) and ion
exchange water and sorbitol, embodiment 2 contained mannitol in an
identical base component, embodiment 3 contained lactitol in
another identical base component, comparison 1 consisted of only a
base component of ethylene glycol and ion exchange water,
comparison 2 additionally contained glucose in a base component
which is identical with comparison 1, comparison 3 additionally
contained mannose in a base material which is identical with
comparison 1, comparison 4 additionally contained lactose in a base
material which is identical with comparison 1, and comparison 5
additionally contained maltose in a base material which is
identical with comparison 1, all at the respectively indicated
weight proportions. TABLE-US-00001 TABLE 1 (wt %) Component Emb1
Emb2 Emb3 Cmp1 Cmp2 Cmp3 Cmp4 Cmp5 ethylene glycol 50 50 50 50 50
50 50 50 ion exchange 50 50 50 50 50 50 50 50 water sorbitol 5.0 --
-- -- -- -- -- -- mannitol -- 5.0 -- -- -- -- -- -- lactitol -- --
5.0 -- -- -- -- -- glucose -- -- -- -- 5.0 -- -- -- mannose -- --
-- -- -- 5.0 -- -- lactose -- -- -- -- -- -- 5.0 -- maltose -- --
-- -- -- -- -- 5.0
[0020] Oxidation deterioration testing (100.degree. C.; 168 hs) was
performed on Embodiments 1-3 and Comparisons 1-5, and their
post-testing electric conductivities were measured. The result of
the measuring is provided in Table 2. TABLE-US-00002 TABLE 2
(electric conductivity: .mu.S/cm) Item Emb1 Emb2 Emb3 Cmp1 Cmp2
Cmp3 Cmp4 Cmp5 Initial conductivity 0.4 OJ 0.2 0.2 0.3 0.4 0.4 0.3
conductivity 3.3 9.7 2.7 42.6 46.3 53.5 47.2 45.6 after test
[0021] The initial electric conductivities of Embodiments 1-3 and
Comparisons 1-5 were all 0.4 .mu.S/cm or below. The electric
conductivities of Comparisons 1-5 after testing were all 40
.mu.S/cm or over, while those of Embodiments 1-3 were all below 10
.mu.S/cm.
EFFECT OF THE INVENTION
[0022] The coolant composition according to the present invention
comprises at least one sugar alcohol in its base component which is
selected from erythritol, xylitol, sorbitol, mannitol, inositol,
quercitol, palatinit, lactitol, maltitol, sucrose, raffinose,
gentinose, melezitose, planteose and stachyose so as to effectively
inhibit oxidation of the base component and inhibit rise of the
electric conductivity of the coolant. Thus, the electric
conductivity of the coolant is maintained low for an extended
period of time and oxidation is effectively inhibited.
* * * * *